3 4 dicqa

Authentic standards (with the purity of above 99.6%) of dicaffeoylquinic acids (1,3-diCQA, 1,5-diCQA, 3,4-diCQA, 3,5-diCQA, and 4,5-diCQA) were purchased from Phytolab (Vestenbergsgreuth, Germany). Mass spectrometry grade (99.9%) methanol was purchased from Romil Pure Chemistry (Cambridge, UK). Mass spectrometry grade formic acid (with the purity of above 96%) was obtained from Sigma-Aldrich (St. Louis, MO, USA). The analytical column used was a reverse-phase Raptor biphenyl (2.1 × 100 mm, 3 µm) column purchased from Restek (Bellefonte, PA, USA).

Authentic standards (with the purity of above 99.6%) of trans-dicaffeoylquinic acid (1,3-diCQA, 1,5-diCQA, 3,4-diCQA, 3,5-diCQA, and 4,5-diCQA) were purchased from Phytolab (Vestenbergsgreuth, Germany). Mass spectrometry grade (99.9%) methanol and acetonitrile were obtained from Romil (Cambridge, UK). Mass spectrometry grade formic acid was purchased from Sigma-Aldrich (St. Louis, MO, USA). A UV light box Model CM-10 was purchased from Spectroline (Westbury, NY, USA). Pinnacle, Raptor, Viva, and Ultra columns were purchased from Restek (Bellefonte, PA, USA) and Kinetex columns were purchased from Phenomenex (Torrance, CA, USA). Chromatographic separation was achieved using nine analytical columns: Pinnacle bi-phenyl and C₁₈ (2.1 × 100 mm, 3 µm), Raptor bi-phenyl and C₁₈ (2.1 × 100 mm, 2.7 µm), Viva bi-phenyl (2.1 × 100 mm, 5 µm), Viva C₁₈ (2.1 × 100 mm, 3 µm), Ultra C₁₈ (2.1 × 100 mm, 3 µm), and Kinetex bi-phenyl and phenyl-hexyl (4.6 × 100 mm, 5 µm).